Beata Kuczynska, also 15, told Sky News: "I know people who are underage who have had sex because they've been influenced by pornography.

"They should make it a lot harder to access."

Dalia Ben-Galim, IPPR associate director, said: "This new polling data shows that pornographic images are pervasive in teenagers' lives and that young women in particular are acutely conscious of how damaging they can be.

"It paints a worrying picture about the way online pornography is shaping the attitudes and behaviour of young people.

"The images and the type of pornography that young people can access quite readily is much more explicit and more violent than young people have been able to access in the past."

The survey also found 72% of 18-year-olds said "pornography leads to unrealistic attitudes to sex".

And 66% of young women and 49% of young men agreed that "it would be easier growing up if pornography was less easy to access for young people".

Matthewos Alem, 17, told Sky News: "It changes young people's minds and their perception on women, how they see them."

But experts warned that the problem should not be blamed just on the internet.

Clinical psychologist Dr Lucy Maddox said: "It's not the only medium where issues of sexual identity and relationships are coming up.

"It's more about the way we talk about these issues in general as a socaiety and in our families, rather than something just to do with technology."